Orthotropic Plate Model for Estimating Deflections in Filled Grid Decks

Concrete filled grid bridge decks exhibit orthogonal elastic properties and significant two-way bending action enabling orthotropic plate theory to determine structural response for these elements. Current American Association of State Highway and Transportation Officials load and resistance factor design (LRFD) specifications employ an orthotropic plate model to predict live load moment in concrete filled grid bridge decks but provide no guidance for computing displacement, a potentially important serviceability consideration. This paper presents equations to approximate the maximum deflection in concrete filled grid bridge decks based on orthotropic plate theory, multiple patch loads, LRFD design truck and tandem load cases, the influence of multiple spans, and the two most common deck orientations.     

Drug Onset Cues, Conditioned Withdrawal, and Drug Relapse: Comment on McDonald and Siegel (2004).

Previous research has shown that under certain conditions environmental cues associated with morphine administration induce drug-opposite conditioned effects that mimic symptoms of opiate withdrawal. R. V. McDonald and S. Siegel (see record 2004-10475-001) extend these observations by demonstrating that acute exposure to a low dose of morphine induces symptoms of opiate withdrawal in rats previously exposed to a high dose of morphine. They hypothesized that early drug onset cues, repeatedly paired with later, larger drug effects, mediate the paradoxical effect of the low drug dose on behavior. They also hypothesized that conditioned withdrawal symptoms induced by the early drug onset cues may mediate the "priming" effect of drugs on relapse and craving. The authors of this comment discuss the degree to which the literature supports this hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Distinctiveness and Correlation in Conceptual Structure: Behavioral and Computational Studies.

Patients with category-specific deficits have motivated a range of hypotheses about the structure of the conceptual system. One class of models claims that apparent category dissociations emerge from the internal structure of concepts rather than fractionation of the system into separate substores. This account claims that distinctive properties of concepts in the living domain are vulnerable because of their weak correlation with other features. Given the assumption that mutual activation among correlated properties produces faster activation in the normal system, the authors predicted a disadvantage for the distinctive features of living things for unimpaired adults. Results of a speeded feature verification study supported this prediction, as did a computational simulation in which networks mapped from orthography to semantics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A 44-GHz monolithic waveguide plane-wave amplifier with improvedunit cell design [using pHEMTs]

A 44-GHz monolithic waveguide plane-wave amplifier (PWA) with improved unit cell design is presented in this paper. The unit cell is a two-stage direct-coupled design and satisfies size, bistability, and stability requirements of the waveguide PWA. The ultra-compact unit cell had a cell size of 0.8 mm², and showed a small-signal gain of 8 dB and an output power of 15 dBm at 44 GHz with a corresponding dc-to-RF efficiency of 10%. A monolithic waveguide PWA using these unit cells showed a “flange-to-flange” gain of 5 dB, an output power of 0.3 W, and an efficiency of 2% at 44 GHz     

Managing Impressions Online: Self-Presentation Processes in the Online Dating Environment

This study investigates self-presentation strategies among online dating participants, exploring how participants manage their online presentation of self in order to accomplish the goal of finding a romantic partner. Thirty-four individuals active on a large online dating site participated in telephone interviews about their online dating experiences and perceptions. Qualitative data analysis suggests that participants attended to small cues online, mediated the tension between impression management pressures and the desire to present an authentic sense of self through tactics such as creating a profile that reflected their "ideal self," and attempted to establish the veracity of their identity claims. This study provides empirical support for Social Information Processing theory in a naturalistic context while offering insight into the complicated way in which "honesty" is enacted online.     

Stressful life events and smoking behaviors in Chinese adolescents: a longitudinal analysis.

The associations between stressful life events and smoking have been established among adolescents in the United States. However, whether these relationships are similar in adolescents from other non-Western cultures is unknown. Understanding these relationships in adolescents may help to provide opportunities to reduce the smoking rates in those cultures by providing positive coping methods that do not include smoking. In this longitudinal study, the associations between nine stressful life events scales and smoking behaviors were examined in a sample of Chinese adolescents. Six of these scales, positive school-related, negative school-related, positive family-related, positive peer-related, negative peer-related, and negative health-related had significantly different means among females and males. Among males, positive school-related stress was a protective factor for smoking susceptibility. Among females, positive school-related stress was a protective factor and negative school-related stress was a risk factor for lifetime smoking, and negative family-related stress was a risk factor for smoking susceptibility. Findings indicate that smoking among male adolescents in China may not be the result of stress; however, in females stress may contribute to the decision to smoke. Future directions are discussed.     

Downward comparison, prejudice, and evaluations of others: Effects of self-esteem and threat.

In two studies, we explored the effects of trait self-esteem and threats to the self-concept on evaluations of others. In Study 1, subjects high, moderate, and low in self-esteem received either success, failure, or no feedback on a test and later evaluated three pairs of targets: ingroups and outgroups based on a minimal intergroup manipulation, those who scored above average and those who scored below average on the test, and themselves and the average college student. Study 2 explored the effects of self-esteem and threat on ingroup favoritism in a real-world setting, campus sororities. Together, the results of these studies indicate that individuals high in self-esteem, but not those low in self-esteem, respond to threats to the self-concept by derogating outgroups relative to the ingroup when the group boundaries have evaluative implications. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The impact of presentation graphics on students’ experience in the classroom

To investigate the benefits and perceived effectiveness of instructional technology, students enrolled in several courses were compared on student evaluations of instruction, grades and an attitudinal questionnaire. The instructors of the courses taught the same course across two successive semesters, using traditional “chalk-and-talk” methods the first semester, and PowerPoint the next; all other techniques (e.g., exams, lecture material) were held constant. Results suggest that organization and clarity, entertainment and interest, professor likeability, and good professor behaviors were enhanced with PowerPoint although final grades were not.     

Saccadic system functioning among schizophrenia patients and their first-degree biological relatives.

In Study 1, 30 schizophrenia Ss and 27 nonpsychiatric comparison Ss were presented with a fixation task, a visually guided reflexive saccade (prosaccade) task, a predictive tracking task (0.4-Hz square wave), and an antisaccade task. The 2 groups did not differ on either the fixation or prosaccade tasks. Schizophrenia Ss had an increased number of errors on the antisaccade task and had decreased rightward visually guided saccade amplitudes during the predictive tracking task. In Study 2, 13 psychiatric comparison Ss and 32 1st-degree biological relatives of the schizophrenia Ss were compared with the schizophrenia Ss and a larger and older sample of nonpsychiatric Ss (n?=?33) on the predictive tracking and antisaccade tasks. The groups did not differ on predictive saccadic tracking. The schizophrenia Ss and their 1st-degree biological relatives made more errors on the antisaccade task than both the nonpsychiatric and psychiatric comparison groups (who did not significantly differ). Results are consistent with the notion that dysfunction of dorsolateral prefrontal cortex, caudate nucleus, or both is related to liability for schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)